Hi there,
In a model/view class, i have a column which is Qt::ItemIsUserCheckable,
in my model's setData(), i do:
if (role == Qt::CheckStateRole && index.column() == VisibleColumn)
{
Qt::CheckState state = value.value<Qt::CheckState>();
item->visible = state == Qt::Checked;
emit dataChanged(index, index);
return true;
}
This works well with Qt-5.7, Qt-5.6 (official binaries), but fails
with Qt-5.5 (official binaries) and Qt-5.6 (KUbuntu-16.10).
The reason is that when i click on the checkbox, QTableView call
setData() with an int-based QVariant (which contains the int value
corresponding to the Qt::CheckState enum member), and:
- In the former case, "value.value<Qt::CheckState>();" converts this
int to the correct Qt::CheckState enum
- In the later case, the int is always converted to "Qt::Unchecked"
(enum value = 0).
The difference of behaviour seems to be caused by the GCC version, not
by Qt version or official binaries vs linux distro.
If i add this debugging message:
qDebug() << value
<< value.value<int>()
<< Qt::CheckState(value.value<int>())
<< value.value<Qt::CheckState>();
Here is what i get:
- Qt-5.6, KUbunutu 16.10
QVariant(int, 0) 0 Qt::CheckState(Unchecked) Qt::CheckState(Unchecked)
QVariant(int, 2) 2 Qt::CheckState(Checked) Qt::CheckState(Unchecked)
- Qt 5.5, Offical binaries
QVariant(int, 0) 0 Qt::CheckState(Unchecked) Qt::CheckState(Unchecked)
QVariant(int, 2) 2 Qt::CheckState(Checked) Qt::CheckState(Unchecked)
- Qt-5.6, Offical binaries
QVariant(int, 0) 0 Qt::CheckState(Unchecked) Qt::CheckState(Unchecked)
QVariant(int, 2) 2 Qt::CheckState(Checked) Qt::CheckState(Checked)
- Qt-5.7, Offical binaries
QVariant(int, 0) 0 Qt::CheckState(Unchecked) Qt::CheckState(Unchecked)
QVariant(int, 2) 2 Qt::CheckState(Checked) Qt::CheckState(Checked)
The workaround for getting this working on all Qt version/compilers is
to convert the variant this way:
Qt::CheckState state = Qt::CheckState(value.value<int>());
I first wonder why does QTableView call setData with an int-based
QVariant for Qt::CheckStateRole while the documentation says that the
underlying data should be Qt::CheckState?
Why is QVariant behaviour changing depending on the compiler version?
Am i missing something or doing something wrong?
Chris
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